DIY Guide: Replacing Your Car's Parking Brake Pads

A fully functional parking brake is not just a convenience; it's a critical safety feature, ensuring your vehicle remains stationary when parked, especially on inclines. Over time, the pads wear down, reducing its effectiveness and potentially leading to dangerous situations. While the task might seem daunting, replacing your parking brake pads is a manageable DIY project that can save you a considerable sum on garage labour. This detailed guide, tailored for the UK home mechanic, will walk you through the process, incorporating essential steps from pad replacement to hydraulic system bleeding and crucial parking brake adjustment.

Understanding Your Parking Brake System

In many modern vehicles, the parking brake pads are integrated into the rear disc brake caliper assembly, or sometimes within a small drum inside the rear brake disc. When you engage the handbrake, a cable mechanism activates these pads, clamping the disc or expanding shoes within the drum to hold the vehicle. Understanding this integration is key, as a parking brake pad replacement often involves working with the entire rear brake assembly.

Essential Tools and Parts

Before you begin, ensure you have all the necessary tools and parts at hand. This will streamline the process and prevent interruptions. You will need:

• Vehicle jack and axle stands
• Wheel chocks
• Thin flat chisel and hammer (for hub cover removal)
• Socket set: 13mm, 27mm (for hub nut), possibly a Hex socket for star bolts
• Open-end spanner: 16mm
• Large knuckle bar (for leverage on tight bolts)
• 3/4 ratchet
• Torque wrench (crucial for correct tightening)
• Piston turning tool (a specific tool for winding back brake pistons)
• Wire brush (for cleaning surfaces)
• New set of brake pads (ensure they are the correct type for your vehicle's rear brakes)
• New rear brake discs (if required, especially if they integrate the ABS ring and bearing)
• Anti-squeal paste
• Thread retainer / Loctite (if new bolts are not supplied)
• Copper grease
• Brake fluid (ensure it complies with your vehicle's specifications)
• Brake bleeding device and bleeding bowls

Safety First: Pre-Job Preparations

Safety is paramount when working on your vehicle's braking system. Always take the following precautions:

1. Position the vehicle onto a flat, level surface.
2. Place wheel chocks securely under the front wheels to prevent any movement.
3. Release the parking brake fully. This is crucial for disengaging the cables and allowing the caliper to be removed easily.
4. Loosen the rear wheel nuts slightly before jacking up the vehicle.
5. Jack up the rear of the vehicle and support it securely on axle stands. Never rely solely on the jack.
6. Remove the rear wheels completely.
7. For safety during brake bleeding, it's advisable to disconnect the vehicle battery. Also, ensure the ABS circuit is free from any hydraulic or electrical faults before proceeding with bleeding.

Step-by-Step Parking Brake Pad Replacement

This section details the removal of old components and the installation of new ones, focusing on the parking brake pads and associated parts.

1. Disconnecting the Handbrake Cable

Locate the handbrake cable at the rear of the brake caliper. This cable needs to be disconnected before you can remove the caliper. It's usually a simple process: pull on the cable to create slack, then push it down and out through its slot on the caliper. Move the disconnected cable out of the way to prevent it from interfering with the next steps.

2. Removing the Brake Caliper

Using a 13mm socket and a 16mm open-end spanner to hold the slider pins, remove the lower caliper stud mounting bolts. These bolts can be quite tight, especially if thread retainer was used previously. Once the bolts are removed, turn the caliper upward or carefully remove it entirely and rest it on a secure part of the rear suspension arm. Ensure it is supported and not left hanging by the brake hose, which could damage the line.

3. Removing the Old Brake Pads

With the caliper out of the way, the old brake pads can simply be removed from their seating. Take note of their orientation for when you fit the new ones, though most pads are designed to fit only one way.

4. Removing the Caliper Hanger and Brake Disc (If Necessary)

If your brake discs are also being replaced, you'll need to remove the caliper hanger. These are typically secured by star bolts and can be extremely tight due to factory-applied thread retainer. Use a large knuckle bar for maximum leverage. Once the hanger is off, you can proceed to remove the brake disc. First, use a thin flat chisel and hammer to tap off the hub cover for the wheel bearing hub nut. Then, use your large bar and a 27mm socket to loosen and fully remove the large nut on the stub axle. The disc, which usually incorporates the bearing and ABS ring, should then pull off easily once the nut is slackened.

5. Retracting the Brake Piston

Before fitting new, thicker pads, the caliper piston must be fully pressed back into its seat. This is a critical step. For many rear calipers, this requires a specific piston turning tool, as the piston needs to be wound back in, not just pushed. Before you start, remove the cap from the brake fluid reservoir under the bonnet. This prevents pressure build-up as the fluid is pushed back into the reservoir. Position the tool correctly and wind the piston fully in until it bottoms out. If it's stiff, you might need to temporarily refit the hanger and caliper to get enough leverage to wind the piston in.

Reassembly: Fitting New Components

1. Preparing the Hanger and Disc

If you removed the hanger, pull out the slider pins and coat them generously with copper grease, then push them back into place, ensuring the rubber bellows are correctly seated. If replacing discs, clean the sub-axle thoroughly, ensuring no dirt is present, then slide the new disc-bearing set onto the stub holder. Tighten the disc-bearing set onto the stud holder to a torque of 15 Nm. Now, tighten the large stud holder nut to a substantial torque of 280 Nm. Finally, fit the hub plugs.

2. Installing New Pads and Caliper

Fit your new brake pads into their respective slots. Apply a thin layer of anti-squeal paste to the back of the pads (where they contact the caliper piston and outer fingers) to prevent future noise. Position the caliper over the new pads. You'll likely encounter some spring pressure from the pad springs, so have your thread retainer (if using existing bolts) and caliper bolts ready. Apply thread retainer to the tips of the caliper bolts. Carefully push the top of the caliper in and start one of the 13mm caliper bolts. Once a few turns are engaged, move to the lower one, push the caliper in, and start the lower bolt. Now, using your 16mm open spanner and 13mm socket, tighten the caliper slide bolts to a torque of 7 Nm.

If you removed the caliper mounting screws, apply Loctite to their tips, position the caliper on the mounting, and tighten these screws to a torque of 105 Nm. Also, tighten any stud bolts to 36 Nm.

Reconnecting and Adjusting the Parking Brake Cable

This step is crucial for ensuring your parking brake functions correctly.

1. Re-attach the parking brake cables into their relative seats on the caliper. This can usually be done by hand, pulling the cable through the slot and securing it.
2. Next, you may need to adjust the cable tension. This often involves removing the central console inside the vehicle to access the parking brake adjuster.
3. Loosen the parking brake adjuster nut as required initially.
4. Re-attach the parking brake caliper side cables and control side cables, ensuring their correct routing and actuation.
5. Fit a new adjuster nut (if supplied) and check that the parking brake cable locks are against their seat.
6. Tighten the adjuster nut until the specified 'X' value is reached. This 'X' value represents the distance between the width of the two black lines coming from the adjuster nut. For example, if the cable lock bracket is black, X = 21mm; if it is golden, X = 16mm.
7. It's important to apply the parking brake control (handbrake lever) several times before making the final 'X' value adjustment. This helps to seat the cables and take up initial slack.
8. Verify that the cable is adjusted to the caliper stop, meaning there's no excessive slack or tension when the handbrake is released.

Brake System Bleeding (Hydraulic Circuit)

After working on the calipers, air can enter the hydraulic system, leading to a spongy brake pedal. Bleeding the brakes is essential to remove this air.

1. Ensure your brake fluid reservoir is topped up to the MAX level. Connect a brake bleeding device to the vehicle's brake fluid reservoir.
2. Fit bleeding bowls onto each caliper's bleeding screw.
3. Bleed the circuit by loosening the bleeding screws in a specific sequence to ensure all air is expelled. The correct order is:
1. Right rear caliper
2. Left front caliper
3. Left rear caliper
4. Right front caliper
4. Follow the instructions for your specific bleeding device. Typically, you'll open the screw, allow fluid and air to escape, then close it before releasing the brake pedal (if bleeding manually) or when the fluid runs clear and bubble-free (with a pressure bleeder).
5. Once bleeding is complete, ensure all bleeding screws are tightened correctly and their protective plugs are fitted.
6. Remove the bleeding device and top up the brake fluid reservoir to the desired level.

Post-Replacement Checks and Road Test

Once all components are reassembled and bled, perform these vital checks:

1. With the engine switched off, press the brake pedal several times until it feels firm. This helps to bring the pistons into contact with the new pads. If the pedal travel feels incorrect, repeat the bleeding procedure.
2. Apply and release the handbrake several times to check its functionality and ensure it holds the vehicle securely.
3. Check the brake fluid level in the reservoir once more.
4. Replace the rear wheels and tighten the wheel nuts to the manufacturer's specified torque.
5. Lower the vehicle safely off the axle stands.
6. Carry out a cautious road test. Begin slowly, applying the brakes gently at first. Gradually increase brake pressure. During this test, perform some instances of ABS braking (e.g., firm braking on a safe, clear road) to verify that the brake pedal travel is regular and the ABS system functions correctly.

Brake Fluid: Operational Precautions

Brake fluid is a critical component of your braking system, and proper handling is essential:

• Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This moisture reduces the fluid's boiling point, leading to potential brake fade, and can cause internal corrosion in the brake lines. Therefore, it should be changed at regular intervals, as specified by your vehicle manufacturer.
• Always use brake fluid that complies exactly with the specifications indicated in your vehicle's handbook. Using the wrong type can cause severe damage to the braking system components.
• Take extreme care not to let brake fluid accidentally drop onto painted, rubber, plastic, or mechanical parts, as it can be corrosive and cause damage. Clean any spills immediately with plenty of water.
• Never use brake fluid from a container that has been open for an extended period of time, as it will have absorbed moisture and its performance will be compromised. Always use fresh fluid from a sealed container.

OEM vs. Aftermarket Parts: A Crucial Consideration

When selecting your replacement parts, particularly brake discs, you might encounter a dilemma between Genuine Renault (OEM) parts and aftermarket alternatives. While aftermarket options can often be more budget-friendly, there are important considerations:

Genuine Renault rear discs often come with the ABS ring and bearing pre-fitted. This is a significant advantage, as issues with aftermarket discs, even those claiming to have an ABS ring, can sometimes lead to the ABS warning light illuminating on your dashboard. This can be a frustrating and time-consuming problem to resolve, potentially requiring further diagnostic work or even re-replacement of the discs.

Furthermore, some aftermarket discs are supplied without the bearing, meaning you would need to purchase and press in new bearings separately, adding to the cost and complexity of the job. Bearings alone can be quite expensive, and pressing them in requires specialised equipment, making any initial saving on the disc price questionable.

While not all aftermarket parts will cause issues, it's a known risk. If you opt for aftermarket discs, it's wise to inquire directly with the seller about their return policy if the ABS light illuminates after fitment. Many suppliers may refuse refunds once the part has been fitted, arguing it cannot be resold, even if the issue only becomes apparent after installation. Genuine parts, while pricier, often offer peace of mind and simplify the overall replacement process.

Frequently Asked Questions (FAQs)

Q: How long does this job typically take?

A: For an experienced DIYer, replacing the rear pads and discs on one side can take around 1.5 hours. If you're tackling it for the first time, allow yourself more time, perhaps 2-3 hours per side, as you'll be learning the process. Remember, rushing can lead to mistakes.

Q: Do I really need special tools like a piston turning tool and torque wrench?

A: Yes, absolutely. A piston turning tool is essential for safely and correctly retracting the rear brake caliper pistons, which typically wind in. A torque wrench is non-negotiable for tightening bolts to the manufacturer's specified settings. Overtightening can strip threads or damage components, while undertightening can lead to bolts loosening, with potentially catastrophic consequences for your brakes.

Q: What if my ABS light comes on after replacing the discs?

A: As discussed, this is a known issue with some aftermarket brake discs, even those that appear to have an ABS ring. The ring might not be correctly calibrated or manufactured to the vehicle's specific requirements. If this happens, you might need to diagnose the ABS system, or in some cases, replace the aftermarket discs with OEM ones to resolve the issue.

Q: Can I just replace the brake pads and not the discs?

A: Yes, if your brake discs are still within their minimum thickness specification and show no signs of excessive scoring, warping, or cracking, you can often replace just the pads. However, it's good practice to inspect the discs thoroughly during any pad replacement. If they are worn, replacing both pads and discs ensures optimal braking performance and longevity.

Q: How often should I change my brake fluid?

A: Brake fluid should typically be changed every two years, regardless of mileage. As it's hygroscopic, it absorbs moisture over time, which degrades its performance and can lead to corrosion within the braking system. Regular changes ensure your braking system remains efficient and safe.

Conclusion

Replacing your parking brake pads, and potentially the associated rear discs, is a rewarding maintenance task that contributes significantly to your vehicle's safety and your peace of mind. By following these detailed steps, paying close attention to safety, using the correct tools, and understanding the nuances of part selection, you can successfully complete this job. Remember, a well-maintained braking system is fundamental to safe driving, so always ensure every component is fitted and adjusted correctly. Happy motoring!

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